AT86RF212 Atmel Corporation, AT86RF212 Datasheet - Page 88

• Manufacturer Part Number: AT86RF212
• Manufacturer: Atmel Corporation

Specifications of AT86RF212

• Max. Operating Frequency: 0 MHz
• Crypto Engine: AES
• Operating Voltage (vcc): 1.8 to 3.6
• Frequency Band: 700/800/900MHz
• Max Data Rate (mb/s): 1
• Antenna Diversity: No
• External Pa Control: Yes
• Power Output (dbm): 10
• Receiver Sensitivity (dbm): -110
• Receive Current Consumption (ma): 9.0
• Transmit Current Consumption (ma): 18 at 5dBm
• Link Budget (dbm): 120

6.7 Listen Before Talk (LBT)
6.7.1 Overview
88
AT86RF212
Note that IEEE 802.15.4–2006 CCA mode 3 defines the logical combination of CCA
mode 1 and 2 with the logical operators AND or OR. This can be selected with:
• Bit 4:0 – CHANNEL
Refer to section 7.8.6.
Register 0x09 (CCA_THRES):
This register sets the ED threshold level for CCA.
Table 6-35. Register 0x09 (CCA_THRES)
• Bit 7:4 – Reserved
• Bit 3:0 – CCA_ED_THRES
For CCA_MODE = 1, a busy channel is indicated if the measured received power is
above (RSSI_BASE_VAL + 2.07 ⋅ CCA_ED_THRES) [dBm]. CCA modes 0 and 3 are
logically related to this result.
Equipment using the AT86RF212 shall conform to the established regulations. With
respect to the regulations in Europe, CSMA-CA based transmission according to IEEE
802.15.4 is not appropriate. In principle, transmission is subject to low duty cycles (0.1
to 1 %). However, according to [5], equipment employing listen before talk (LBT) and
adaptive frequency agility (AFA) does not have to comply with duty cycle conditions.
Hence, LBT can be attractive in order to reduce network latency.
Minimum Listening Time
A device with LBT needs to comply with a minimum listening time, refer to section
9.1.1.2 of [5]. Prior transmission, the device must listen for a receive signal at or above
the LBT threshold level to determine whether the intended channel is available for use,
unless transmission is pursuing acknowledgement.
A device using LBT needs to listen for a fixed period of 5 ms. If the channel is free after
this period, transmission may immediately commence (i.e. no CSMA is required).
Otherwise, a new listening period of a randomly selected time span between 5 and 10
ms is required. The time resolution shall be approximately 0.5 ms. The last step needs
to be repeated until a free channel is available.
Bit
Name
Read/Write
Reset Value
Bit
Name
Read/Write
Reset Value
o
o
7
Reserved
R/W
0
3
CCA_ED_THRES
R/W
0
CCA_MODE = 0
CCA_MODE = 3
6
Reserved
R/W
1
2
CCA_ED_THRES
R/W
1
for logical operation OR, and
for logical operation AND.
5
Reserved
R/W
1
1
CCA_ED_THRES
R/W
1
8168C-MCU Wireless-02/10
4
Reserved
R/W
1
0
CCA_ED_THRES
R/W
1